A chemodosimeter approach for selective colorimetric and fluorimetric cyanide detection using coumarin based fluorescent dyes

Abstract

New coumarin based allylidenemalononitrile-aminophenyl conjugated fluorescent dyes having donor-π-acceptor-donor (D-π-A-D) system (Dyes 1, 2 and 3) were synthesized and characterized using 1H/13C-APT NMR and HRMS. Interestingly, dye 3 (diacetamide derivative) was obtained as a mixture of E/Z isomer. Dye 3 was investigated by 1H NMR within two solvents with different polarity (DMSO-d6 and Chl-d1) and exposed UV irradiation to observe any configurational changes. The absorption and emission properties of the dyes were determined in various solvents with different polarity. The anion sensitivity and selectivity of the dyes were studied with various anions in DMSO, and their interaction mechanisms were evaluated by spectrophotometric and 1H NMR titration techniques. All three dyes only interacted with cyanide via Michael reaction and the main absorption maxima showed hypsochromic shifts and emission intensity quenched. Moreover, investigation of cyanide sensitivity of the dyes was studied in aqueous media as a mixture of DMSO:water (7:3, v/v). Also, all these results can be detected with the naked eye due to the observed color of the dyes changes from pink to yellow. Additionally, DFT and TDDFT studies were performed to support structural and absorption spectral properties of the dyes.